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在诸多岩土工程如高放核废料处置、地热资源开发等应用中需要考虑软岩的长期力学特性,而温度升高会对软岩材料的蠕变破坏特性产生复杂影响,建立能反映蠕变破坏特性的本构模型具有理论价值和现实意义。从连续介质力学入手,基于下负荷面剑桥模型和等价应力的概念,建立了能描述软岩在温度作用下蠕变过程的热弹黏塑性模型。利用自主开发的仪器,采用大谷石进行了不同围压下的三轴蠕变试验,并对模型进行了验证。多种实验结果表明,材料在不同应力状态下,存在最优温度使得蠕变破坏最慢,此外,受温升影响时存在蠕变破坏加快和减慢两种现象,提出的模型能统一描述这两种现象。分析了模型特性,总结了不同材料参数和应力状态对蠕变规律的影响。
Long-term mechanical properties of soft rock need to be considered in many geotechnical engineering applications such as high-level nuclear waste disposal and geothermal resource development. However, the elevated temperature will have a complex impact on the creep and failure characteristics of soft rock materials, The constitutive model of damage characteristics has theoretical value and practical significance. Starting from the continuum mechanics, based on the concept of lower load surface Cambridge model and equivalent stress, a thermoelastic visco-plastic model that can describe the creep process of soft rock under temperature is established. Triaxial creep tests under different confining pressures were carried out by using Oguchi stone with self-developed instruments, and the model was verified. A variety of experimental results show that under the different stress conditions, the material has the optimal temperature so that the creep damage is the slowest. In addition, there are two phenomena that the creep damage is accelerated and slowed down when the temperature is affected. The proposed model can describe this uniformly Two phenomena. The characteristics of the model are analyzed and the influence of different material parameters and stress states on the creep law is summarized.